In March 2015 alone, American police officers killed 115 people, according to data collected by KilledbyPolice.net. KilledByPolice.net is a crowdsourced database of police-involved killings. To put this data in perspective, many other wealthy nations need years before they see 115 police-related killings. Even adjusting for population, these numbers are stark. As The Economist reported, an American is 100 times more likely than a UK resident to be shot by police. It also pointed out that between 2010 and 2014, the city of Albuquerque's police force shot and killed seven times more people than police in England and Wales shot and killed, combined.

Another police-related killing.

Prosecutors filed charges Tuesday against North Charleston, S.C., police officer Michael T. Slager for the murder of Walter L. Scott, an unarmed Black man who was pulled over for a broken taillight and then shot repeatedly by Slager after fleeing the scene. The tragedy sparked outrage all over the United States, which still hasn't recovered from the police-related deaths of Eric Garner and Michael Brown in Ferguson, Mo.

We don't even have accurate data on this problem.

There is no official database of American deaths at the hands of law enforcement. The Justice Department's Bureau of Justice Statistics (BJS) does collect data on officer-related deaths, but it's considered inadequate because of inconsistent collection methods that depend on reports from varying state agencies. That data, released earlier this year, reported that an estimated 928 people are killed by police each year. A BJS-requested independent analysis, however, found that this data fails to capture as much as 28 percent of police-related deaths. A recent study by Human Rights Data Analysis Group (HRDAG) found the number to be close to 1,240 deaths a year.

Last month, the president's task force on policing, created in the wake of unrest in Ferguson and New York, recommended that the Department of Justice begin to better report data on police use of excessive force. The report noted that the Justice Department is already mandated by law to collect this data, but Congress has not allocated adequate funding to fulfill this obligation.

Patrick Ball, executive director of HRDAG, told FiveThirtyEight that the BJS underestimates the true number of deaths by police officers because it doesn't match records with missing information or audit its data. Ball also said its use of only two databases inevitably leads to discrepancies. That's why sources like KilledByPolice.net have stepped in to fill this role through crowdsourcing.

As discussed by FiveThirtyEight, getting a more accurate picture of how many people are killed annually by police officers could give us the necessary insight to try to prevent senseless future deaths, "[T]he real significance of the report is in telling us what we — including the president and the attorney general — still don’t know."